Ill. Admin. Code tit. 35, § 220.220
a) Each owner or operator of an MSW landfill having a design capacity equal to or greater than 2.5 million Mg and 2.5 million m3, and a calculated NMOC emission rate equal to or greater than 50 Mg/yr, must install and operate a gas collection system that meets the requirements of either subsection (b), (c), (d), or (e) of this Section and:
2) Collects gas from each area, cell, or group of cells in the landfill in which the initial solid waste has been placed for a period of:
b) Active Collection Systems:
1) Active collection wells, horizontal collectors, surface collectors, or other extraction devices shall be sited at a sufficient density throughout all gas producing areas using the following procedures:
D) The placement of gas collection devices determined in subsection (b)(1)(A) of this Section shall control all gas producing areas, except as provided by this subsection (b)(1)(D).
ii) Any nonproductive area of the landfill may be excluded from control provided that the total of all excluded areas can be shown to contribute less than 1 percent of the total amount of NMOC emissions from the landfill. The amount, location, and age of the material shall be documented and provided to the Agency upon request. A separate NMOC emissions estimate shall be made for each section proposed for exclusion, and the sum of all such sections shall be compared to the NMOC emissions estimate for the entire landfill, as calculated pursuant to Section 220.260 of this Subpart. Emissions from each section shall be computed using the following equation:

where:
| Qi | = | NMOC emission rate from the ith section, Mg/yr |
| k | = | methane generation rate constant, yr-1 |
| Lo | = | methane generation potential, m3 per Mg solid waste |
| Mi | = | mass of degradable solid waste in the ith section, years |
| ti | = | age of the solid waste in the ith section, years |
| CNMOC | = | concentration of NMOC, ppmv |
| 3.6x10-9 | = | Conversion factor |
The values for k and CNMOC determined in field testing shall be used, if field testing has been performed in determining the NMOC emission rate or the radii of influence (the distance from the well center to a point in the landfill where the pressure gradient applied by the blower or compressor approaches zero). If field testing has not been performed, the default values for k, Lo, and CNMOC provided in Section 220.260(a)(1) of this Subpart shall be used. The mass of nondegradable solid waste contained within the given section may be subtracted from the total mass of the section when estimating emissions, provided the nature, location, age and amount of the nondegradable material is documented.
2) The gas collection devices shall be constructed using the following equipment or procedures:
3) The landfill gas shall be conveyed to a gas control system through the collection header pipe(s). The gas mover equipment shall be sized to handle the maximum gas generation flow rate expected for the period of intended use pursuant to Section 220.250(h) of this Subpart using the following procedures:
c) Passive Collection Systems:
d) Alternate Collection Systems:
An owner or operator seeking to install an alternate gas collection system shall demonstrate to the Agency that such collection system is capable of capturing the maximum expected gas flow rate from the entire area of the MSW landfill, for the period required in Section 220.250(h) of this Subpart, as calculated pursuant to Section 220.240(a) of this Subpart, and in an equivalent manner to that required by this Section. Any alternate gas collection system must be approved by the Agency. Such alternate shall be effective only when included in a federally enforceable permit or approved as a SIP revision. The alternate shall include any alternate procedures for collection, control, compliance, monitoring, operation, testing, reporting, and recordkeeping that are appropriate.
e) Alternate Emissions Standard:
Pursuant to Section 28.1 of the Act [415 ILCS 5/28.1], and in accordance with 35 Ill. Adm. Code 106, Subpart G, provisions for adjusted standards, adjusted standards for alternate emissions standards or alternate emissions standards with an alternate compliance schedule shall be granted by the Board, to the extent consistent with federal law. An owner or operator seeking an alternate emissions standard or an alternate emissions standard with an alternate compliance schedule must demonstrate to the Board that, with respect to the MSW landfill, the control requirements meet one or more of the criteria listed in this subsection (e) pursuant to 40 CFR 60.24(f). Any such request must be approved by the Board. Such alternate shall be effective only when included in a federally enforceable permit or approved as a SIP revision. Any alternate shall include any procedures for collection, control, compliance, monitoring, operation, testing, reporting and recordkeeping that are appropriate and a demonstration that the control requirements, as contained in this Subpart, as they apply to the MSW landfill, meet one or more of the following criteria: